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Insect Bore Hole?

Insect Bore Hole?
Sitka County, Alaska, USA
July 3, 2008
I am guessing this trail through the wood was made by an insect (beetle?) of some sort. It was in a rotting sitka alder (Alnus viride ssp. sinuata) branch, and presumably the branch broke where it did because the boring weakened the wood there relative to surrounding parts. I'm interested in any thoughts/ideas about what may have done this.


Moved from Unidentified Wood Borings.
The dark-stained tunnel does suggest an ambrosia beetle, now that you mention it. The species you mention are all in subtribe Xyleborina, but I'm not familiar enough with this group to say what the most specific safe placement for this image would be.

Hey Matt this looks just like
Hey Matt this looks just like the mining of the Granulate Ambrosia beetle, formaly the Asian Ambrosia beetle, Xylosandrus crassiusculus. I can't tell you for sure that it is in fact that species but I have dissected a couple hundred minings of X. crassiusculus, X. germanus and Cnestus mutilatus. This looks more like the mining of the first two which is caused by a single female.

Moved from ID Request. Almost certainly some kind of beetle, and it's probably possible to tell what kind based on this pattern, the characteristics of the frass, and the fact that it was in an alder. I hope someday the right person will see this "unidentified wood borings" section...

One of the things I wonder is the path that was taken. Was the curvy spur just below the middle the starting point, with the travel making the 'S' to the right, left, then back to the right until reaching the layer it apparently preferred and going all the way around prior to exiting?

Looking back at the original picture at the full detail, it appears that holes branched off in both directions along the branch longitudinally. I'm not sure if that would imply more than one individual, or if one would return to the same place repeatedly.

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